Polarity control system

ABSTRACT

A system for controlling the transmission of electrical power between a D.C. power source and a load. The system includes a circuit having indicator lamps for visually indicating the polarity of the power source and of the load. Relays are utilized to prevent power transmission when the source and the load are improperly connected to the circuit. The circuit includes normally closed contacts of one relay in series with the coil thereof and a resistor in parallel with the normally closed contacts so that when the coil is energized, the voltage applied to the coil is automatically reduced during operation.

United States Patent Carlson 5] Apr. 25, 1972 [54] POLARITY CONTROLSYSTEM 3,34l,762 9/1967 Rockoff ..320 25 x [72] Invemor: Arthur E.Carlson Newton Iowa 3,343,057 9/1967 Smith ..320/25 X [73] Assignee:Winpower Manufacturing Company Primary Examiner-William M. Shoop, Jr.

Assistant Examiner-Robert J. Hickey l 7 [22] ed Dec 4 l9 0Attorney-Molmare, Allegrettl, New1tt& Witcoff [21] App]. No.: 95,264

[57] ABSTRACT U.S. I A system for controlling the transmission ofelectrical power 307/127 between a DC. power source and a load. Thesystem includes [51] lnLCl. "H021 7/00 a circuit having indicator lampsf visually indicating the [53] Field of Search ..320/22, 25, 26, 48;307/86, polarity of the power source and f the load. Relays are utih307/127; 317/39 ized to prevent power transmission when the source andthe load are improperly connected to the circuit. The circuit in- [56]References Cited cludes normally closed contacts of one relay in serieswith the UNITED STATES PATENTS coil thereof and a resistor in parallelwith the normally closed contacts so that when the Col] 15 energized,the voltage applied 3,28 1,8 l 6 RaymOnd to the coil is automaticallyreduced during operation 3,308,365 3/1967 St. John... ..320/25 3,267,3018/1966 Gignac ..320/25 X 6 Claims, 3 Drawing Figures Patented April 25,1972 2 Sheets-Sheet 2 i r MW M M Ru; 2/ r i; #H m. 1W llll w 9/BACKGROUND OF THE INVENTION This invention relates generally to anelectrical power transmission control circuit. As heretofore wellknown'in the art, numerous devices such as heavy construction equipment,road vehicles, farm implements and motor powered boats require a supplyof electrical power generally in the form of a battery for starting theengines which drive these devices. When the energy level of such abattery is low or when the engines of the various devices are cold andhave not been used for a time, the electrical power from the battery isoften insufficient to perform the required task.

To supply the energy required, jumper cables are often used to connect apower source to the battery or electrical load which is to be energized.This connection must be made accurately with the positive pole of theload connected to the positive pole of the power source and the negativepole of the load connected to the negative pole of the power source. Ifa mistake is made in the connection, the results range from adverse todisasterous. For example, a battery may be damaged, the electricaljumper cables may be destroyed or the power source may be damaged. Also,the operator connecting the jumper cables and others in proximity to theoperation may be seriously injured by a short in the electrical systemwhich can cause electrical arcing. Accordingly, it is desirable toprovide an electrical control system which will allow safe transmissionof electrical power from a source to a load. It is also desirable toprovide such a device which will be simple and economic to construct andoperate.

SUMMARY OF THE INVENTION source In a principal aspect, the presentinvention takes the form of an electrical circuit for controlling thetransmission of power from a power source to an electrical load. Thecircuit includes means responsive to the polarity of the source and theload for conducting power from the source to the load only when both thesource and the load are connected with predetermined polarities to thecircuit. The circuit also includes means for indicating the polarity ofboth the source and the load.

According to a further feature of the invention, a manually operableswitch means is provided to circumvent the load polarity responsivemeans so that when the load has no detectable polarity, power may stillbe transmitted thereto from the power source. According to anotherfeature of the invention, a second manually operable switch is providedas a safety measure to prevent power transmission until the operatoractuates the second switch. The specific means used to control theconducting of power from the source to the load include a lamps, placedin parallel across the input and output ports of the control circuit.

BRIEF DESCRIPTION OF THE DRAWINGS These and other features and objectsof theinvention may be more clearly understood through a study of adetailed description which follows. During the course of thisdescription, reference will frequently be made to the attached drawingsin which:

FIG. 1 is a perspective view of the electrical power supply, electricalload and the power transmission control system of this invention;

FIG. 2 is a circuit diagram of one simplified electrical circuitemploying the features of this invention; and

FIG. 3 is a circuit diagram of a second preferred embodiment of acircuit employing the features of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG.1, of a power source in the form of a DC. arc welder 10 is shown. Thewelder 10 is of the type commonly used in the construction industry andis but one exam ple of an electrical DC. power source which may be usedin this invention. The welder 10 is enclosed by a hood 12 and issupported by a chassis l3 and wheels 14. The welder 10 is provided withelectrically conductive output cables 16 extending outwardly from thewelder. The DC. power transmission control circuit (not shown in FIG. 1)is enclosed in a light-weight, portable housing 20 which may be formedof heavy gauge steel and coated with enamel to enhance its appearance.The housing 20 includes a hinged lid 21 connected thereto and a latchmechanism 21a for securing the lid 21.

Extending outwardly from either side of the housing 20 are electricallyconductive input bus bars 22 which are also connected to the input portof the power transmission control circuit (not shown in FIG. 1). Alsoextending outwardly from the sides of the housing 20 are electricallyconductive output terminals 24. It is to be understood that the outputterminal 24 on the left side of the housing 20 is identical to theoutput terminal 24 on the right side, although the left output terminal24 does not appear in FIG. 1.

The electrical load shown in FIG. 1 is a battery 26 although the loadmay also take other forms, for example, the electrical starting systemof a vehicle (not shown). It should also be noted that the electricalpower source which takes the form of a DC. welder 10 in FIG. 1 may besubstituted by other devices, for example, a booster battery (notshown).

Referring generally to the simplified circuit diagram shown in FIG. 2, apower control circuit 28 is shown. The circuit includes an input porthaving upper and lower input terminals 30 and an output port havingupper and lower output terminals 32. Connected in parallel to the inputterminals 30 is a variable DC. voltage source 34. An electrical load 36is in parallel with the output terminals 32. As has been explainedpreviously, the power source 34 may take the form of the DC arc welder10 and the electrical load 36 may take the form of the battery 26.

The circuit 28 includes a means 37 responsive to the polarities of theload 36 and the source 34 for conducting power therebetween only whenthe load 36 and source 34 are connected to the circuit 28with-predetermined polarities. The polarity responsive means 37 utilizesrelays R1 and R2. Contacts 38 of relay R1 are in series between theupper input terminal 30 and upper output terminal 32. The solenoid 40 ofRelay R1 is connected in series with contacts 42 of the relay R2 anddiode 44. The series connected solenoid 40, contacts 42 and diode 44form a branch 46 which is connected in parallel with source 34 acrossinput terminals 30. The solenoid 48 of relay R2 is in series with adiode 50 to form a branch 52 which is in parallel with the load 36across output terminals Because of the polarity of diode 50, no currentwill flow through the solenoid 48 of relay R2 until the load 36 iscorrectly aligned with its positive pole connected to the upper terminal32 and its negative pole 32 connected to the lower terminal 32.Therefore, the solenoid 40 of relay R1, in series with the normally opencontacts 42 of relay R2 cannot be energized until the load 36 isproperly connected. After load 36 is properly connected, contacts 38 ofrelay R1 remain open until the source 34 is properly connected becausediode 44 allows only unidirectional current in branch 46. Accordingly,both the source 34 and the load 36 must have corresponding polaritiesbefore the circuit 28 will conduct power therebetween.

A second circuit 54 employing the principals of this invention is shownin FIG. 3. The elements of circuit 54 which are identical to those ofFIG. 2 will be described with identical numerals. Branch 46 includes, inaddition to solenoid 40 of relay R1, contacts 42 of relay.R2, and diode44, a manually operable switch 56 in parallel with contacts 42 and amanually operable switch 58 in series in branch 46. The switch 56 isprovided to circumvent the contacts 42 of relay R2 when the voltage ofthe load 36 is undetectable as for example in the case of a batteryhaving little or no energy. The switch 58 is provided to allow anoperator final discretion as to Whether the circuit between the load 36and source 34 should be completed.

Branch 52 in addition to the solenoid 48 and diode 50 also includesnormally closed contacts 60 of relay R2 in series in the branch 52 and apair of series connected resistors 62 and 64 in parallel across thecontacts 60. A manually operable switch 66 is in parallel across theresistor 64 and is mechanically linked to a switch 68 which will be morefully described below. After the solenoid 48 of relay R2 is energized bythe properly connected load 36, the normally closed contacts 60 of relayR2 open and channel current through resistors 62 and 64, thus reducingthe voltage applied to the solenoid 48 during operation.

The circuit 54 also includes means 69 for indicating the polarity of thepower source 34 and a means 70 for indicating the polarity of the load36. The indicator means 69 in part takes the form of a diode 70,indicator lamp 71 and resistor 72, all in series to form a branch 73.The branch 73 is in parallel with the power source 34 across inputterminals 30. A series connected diode 74 and indicator lamp 76 areconnected in parallel across the diode 70 and lamp 71 with diode 74being poled oppositely to diode 70. As may be seen, when the positivepole of source 34 is connected to the upper input terminal 30, indicatorlamp 71 will be energized. When the connection is reversed, indicatorlamp 76 is energized.

Referring to the tool box 20 shown in FIG. 1, the lamps 71 and 76 arecolor coded for greater convenience. For example, lamp 71 may have agreen translucent plastic cap 78 to show a correct connection and lamp76 may have a red translucent plastic cap 80 to show an incorrectconnection.

The indicator means 70 is similar to indicator means 69 and includes adiode 82, an indicator lamp 84 and a resistor 86 series connected toform a branch 88. The branch 88 is in parallel with the load 36 acrossthe output terminals 32. A series connected diode 88 and indicator lamp90 are in parallel across diode 82 and lamp 84 with diode 88 beingoppositely poled to diode 82. The resistor 86 is in parallel with theswitch 68. As may be seen, when the load 36 is correctly connected tothe circuit 54 with its positive pole corresponding to the upperterminal32, indicator lamp 84 will be energized. When the connection isreversed, lamp 90 is energized.

' Referring to the tool box 20 shown in FIG. 1,'the lamps 84 and 90 maybe color coded. For example, lamp 84 may have a green translucentplastic cap 92 to show a correct connection and lamp 90 may have a redtranslucent plastic cap 94 to show an incorrect connection.

The mechanically linked switches 66 and 68 are provided to match thevoltage of source 34 to the voltage of load 36. The switches 66 and 68cooperate with the resistors 62, 64 and 86 to allow the circuit to beoperated with loads having different voltage ratings.

As an added feature of this invention, a circuit breaker or toggleswitch 96 is shown in series with an ammeter 97 and a diode 98. Theseseries connected elements are in parallel across the contacts 38 ofrelay R1 with the diode 98 poled to conduct current from source 34 tothe load 36. As may be seen, these elements circumvent the requirementsof relay R1. Accordingly, the circuit may be used with a load 36, havingno voltage at all and the current supplied to such a system may beeasily monitored.

While in the foregoing descriptions of the circuits 28 and 54 sufficientto make and use the same have been made, a description of the method ofuseof the circuit 54 will be detailed for greater clarity.

The circuit 54 may be used in a variety of applications such as (l) in anormal vehicle starting operation, (2) to start a vehicle having a deadbattery or having no battery at all and (3) to charge a battery. Inorder to start a vehicle, the

mechanically linked switches 66 and 68 may be operated by a toggle 100shown on the control panel 102 of the tool box 20. The toggle should beset to the voltage of the vehicle electrical system which is theelectrical load 36. The circuit breaker 96 is operated by a secondtoggle 104 and should be open or in the off position. In order to startthe power transmission, the DC. are welder 10 or other power supplyshould be connected to the input terminals 30 of the circuit 54. Thiscan be done by connecting the jaws 106 of the output cables 16 to theinput bus bars 22 of the tool box 20. Assuming that the positiveterminal of the power source 34 is connected to the upper input terminal30 of the circuit 54, a current will be conducted through the diode 70,indicator lamp 71 and resistor 72. The green cap 78 is illuminated ifthe connection is correct and the red cap is illuminated if theconnection is incorrect.

After the correct polarity connection of the power source 34 isestablished, the electrical load 36 is connected to the circuit.Assuming that the load has a detectable voltage, a correct connectionwill illuminate green cap 92 and an incorrect connection will illuminatered cap 94.

In the practical operation of the circuit 54, a push-button control 112is provided to operate the switch 58. The pushbutton control 112 isconnected through a control cable 114 to the control panel 102. A button116 biases switch 58 to prevent the transmission of power between thesource 34 and the load 36. When button 116 is depressed, the normallyopen switch 58 is closed. Until the button 116 is depressed, no currentwill flow through the solenoid 40 of the relay R1. The relay contacts 38of relay R1 will remain open preventing power transmission.

When the operator wishes to start a vehicle he connects the vehicleelectrical system and the power source to the circuit 54 as has beendescribed. Having done this, he may take the push-button control 112 tothe vehicle, energize the starter of the vehicle (not shown) and thendepress the push-button 116. If the starter fails to operate, thepush-button 116 should be released and the starting circuitde-energized. A higher setting should then be made on the power source34 and the operation repeated until the vehicle commences to function.The process for starting a vehicle with a dead battery or with nobattery at all isas follows. Mechanically linked switches 66 and 68should be set at the voltage at the vehicle electrical system. Thecircuit breaker 96 should be off. The power source 34 should beconnected to the circuit 54 as has been previously explained. Since thevehicle to be started has a dead battery or no battery at all, therewill be no detachable polarity from the load 36. Therefore, the loadpolarity indicating means 70 will be inoperative and the polarity of theload 36 must be carefully checked by the operator. Next the operatorshould take the push-button control device 112 with him to the vehicle.Because no current is developed from the load 36, no current will flowthrough the solenoid 48 of the relay R2 and the contacts 42 of the relayR2 will remain open. Therefore, a second operator should be stationed atthe toggle to close the manually operable switch 56 which acts tocircumvent the open contacts 42. The operation should then be repeatedas described above until the engine starts.

In the battery charging operation, the mechanically linked switches 66and 68 should be set at the voltage of the battery 26 to be charged. Thecircuit breaker 96 should be off. Next the battery 26 and power source34 should be connected to the circuit 54 as previously described. Thepower source should be operated at a low setting and the circuit breaker96 should then be closed by operating the toggle 104. In this mannerthere is no need for the relay contacts 38 of relay R1 to be closed and,therefore, the push-button 116 need not be depressed. Thus the operatoris not. required to expend unnecessary effort during the time consumingbattery charging operation. This operation is intended to deliver apartial charge to a low charged battery, and to enable the operator tomonitor the current delivered thereto.

The foregoing description of this invention is meant to be illustrativeof the principles of this invention. It is to be understood that otherembodiments may be made according to the principles of this inventionwithout departing from the true spirit and scope thereof,

What is claimed is:

l. A circuit for controlling the of electrical energy from a DC. powersource to an electrical load comprising, in combination:

an input port adapted for electrical connection to said DC. power sourcehaving a first input terminal and a second input terminal;

an output port adapted for electrical connection to said load, having afirst output terminal and a second output terminal;

a first relay having a relay coil in series with a first diode, saidseries connected first relay coil and first diode being connected acrosssaid input port between said first input terminal and said second inputterminal, said first diode being poled to conduct current only from saidfirst input terminal to said second input terminal, said first relayalso having a pair of normally open contacts connected between saidfirst input terminal and said first output terminal;

a second relay having a coil connected in series with a second diode,said series connected coil of said second relay and said second diodebeing connected in parallel across said output part between said firstoutput terminal and said second output terminal, said second diode beingpoled to conduct current only from said first output terminal towardsaid second output terminal, said second relay also having a first pairof normally open contacts in series with the coil of said first relay,and a second pair of normally closed contacts connected in series withthe coil of said second relay; and

at least one resistor connected in parallel across the second pair ofnormally closed contacts of said second relay such that when said loadand said DC power source are correctly connected to said circuit, thecoil of said second relay is energized and said second pair of normallyclosed contacts in series with said coil of said second relay open toreduce the voltage applied to the coil of said second relay and the pairof normally open contacts of said second relay are closed to allow flowof current through the coil of said first relay to thereby energize thecoil of said first relay and close the normally open contacts of saidfirst relay connected between said first input terminal and said firstoutput tenninal for conducting power therethrough.

2. The circuit as set forth in claim 1 including means for indicatingthe polarity of said power source when said source is connected acrosssaid input port.

3. The circuit as set forth in claim 1 including means for indicatingthe polarity of said load when said load is connected to said outputport.

4. A circuit as set forth in claim 1 including manually operable meansfor circumventing the coil of said second relay such that power may beconducted to said load when said load has no detectable voltagethereacross.

5. The circuit as set forth in claim 1 including a switch biased toprevent conducting the transmission of power from said source to saidload until said biased switch is actuated.

6. The combination as set forth in claim 5 including a toggle switch forconducting power between said source and said load when said switch isactuated.

1. A circuit for controlling the of electrical energy from a D.C. powersource to an electrical load comprising, in combination: an input portadapted for electrical connection to said D.C. power source having afirst input terminal and a second input terminal; an output port adaptedfor electrical connection to said load, having a first output terminaland a second output terminal; a first relay having a relay coil inseries with a first diode, said series connected first relay coil andfirst diode being connected across said input port between said firstinput terminal and said second input terminal, said first diode beingpoled to conduct current only from said first input terminal to saidsecond input terminal, said first relay also having a pair of normallyopen contacts connected between said first input terminal and said firstoutput terminal; a second relay having a coil connected in series with asecond diode, said series connected coil of said second relay and saidsecond diode being connected in parallel across said output part betweensaid first output terminal and said second output terminal, said seconddiode being poled to conduct current only from said first outputterminal toward said second output terminal, said second relay alsohaving a first pair of normally open contacts in series with the coil ofsaid first relay, and a second pair of normally closed contactsconnected in series with the coil of said second relay; and at least oneresistor connected in parallel across the second pair of normally closedcontacts of said second relay such that when said load and said D.C.power source are correctly connected to said circuit, the coil of saidsecond relay is energized and said second pair of normally closedcontacts in series with said coil of said second relay open to reducethe voltage applied to the coil of said second relay and the pair ofnormally open contacts of said second relay are closed to allow flow ofcurrent through the coil of said first relay to thereby energize thecoil of said first relay and close the normally open contacts of saidfirst relay connected between said first input terminAl and said firstoutput terminal for conducting power therethrough.
 2. The circuit as setforth in claim 1 including means for indicating the polarity of saidpower source when said source is connected across said input port. 3.The circuit as set forth in claim 1 including means for indicating thepolarity of said load when said load is connected to said output port.4. A circuit as set forth in claim 1 including manually operable meansfor circumventing the coil of said second relay such that power may beconducted to said load when said load has no detectable voltagethereacross.
 5. The circuit as set forth in claim 1 including a switchbiased to prevent conducting the transmission of power from said sourceto said load until said biased switch is actuated.
 6. The combination asset forth in claim 5 including a toggle switch for conducting powerbetween said source and said load when said switch is actuated.